SAM4L Datasheet, PDF (703/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/L2
27.8 Functional Description
27.8.1
Transfer Format
The data put on the TWD line must be 8 bits long. Data is transferred MSB first; each byte must
be followed by an acknowledgement. The number of bytes per transfer is unlimited (see Figure
27-4).
Each transfer begins with a START condition and terminates with a STOP condition (see Figure
27-4).
• A high-to-low transition on the TWD line while TWCK is high defines the START condition.
• A low-to-high transition on the TWD line while TWCK is high defines a STOP condition.
Figure 27-3. START and STOP Conditions
TWD
TWCK
Start
Stop
Figure 27-4. Transfer Format
TWD
TWCK
27.8.2 Operation
Start Address R/W Ack
Data
Ack
Data
Ack Stop
The TWIM has two modes of operation:
• Master transmitter mode
• Master receiver mode
The master is the device which starts and stops a transfer and generates the TWCK clock.
These modes are described in the following chapters.
42023C–SAM–02/2013
703